Edwaed p



(No Model.)

B. P. THOMPSON.

PROCESS OF TREATING ELECTRIC LIGHT EILAMEN'I-S;

No. 370,992.- Patented Oct. 4, 1887.

- awuc'wtoz Q/VMweooQ/o UNITED STATES PATENT OFFICE.

EDWARD P. THOMPSON, OF ELIZABETH, NEW JERSEY.

PROCESS OF TREATING ELECTRIC-LIGHT FILAMENTS.

SPECIFICATION forming part of Letters Patent No. 370,992. dated October4, 1887.

Application filed September 15, 1886. Serial No. 213.570. (No model.) I

To all whom, it may concern.-

Be it known that I, EDWARD P. THOMPSON, a citizen of the United States,residing in Elizabeth, in the county of Union and State of New 'Jersey,have invented certain new and useful Improvements in Processes ofTreating Electric-Light Filaments, of which the following is aspecification.

Theobject of the invention is to so treat the filaments employed inincandescent electric lights as to render them capable of longerendurance and to give them greater strength.

The invention consists in giving to the filaments a permanent set, andthis is accom' plished preferably by passing an electric current throughthe same of such strength as to raise them to a sufficient temperatureto cause them to break. Having once been broken in this manner, apermanent set is given to the filament, and subsequently the filamentwill not be broken except by an application of an equal amount of heat,which in practice will never occur. The broken filament may be mended'by a deposition of carbon or hydrocarbon, or it may be made of suchlength as to admit an end being broken off without rendering it shorterthan is required in practice. The extreme temperature to which thefilament is subjected drives off every particle of gas from the carbon,and gives the permanent set to the molecules by reason of the mechanicalstrain to which it is at the same time subjected, and it causes thecarbon to pass through a viscous state, and when it cools it is moredense. The carbon thus treated is also found capable of being bent andstrained, with less liability to break. It also throws off less carbon,and thus prevents the interior of the globes from becoming so quicklyblackened.

In the accompanying drawings, Figure 1 illustrates a method of breakingthe filaments. Fig. 2 represents the filaments in the process of beingmended.

Referring to these figures, A and A represent two clamps for receivingthe ends of an elongated filament, B, and placing it in circuit with asuitable source of electricity, G, capable of producing such current aswill raise it to an intense heat. The filament may be broken simply bythe application of heat in this manner, or a refracting contact-point,a, may be applied against its surface at a point near the clamp A, forinstance, and this will insure that when the filament is broken by heatit will be at the point where the contactpoint a touches it. This beingbeyond the points b N, where a filament of the normal length wouldterminate, the breaking of the filament will not injure its usefulness.If, on the other hand, the filament should be broken without referenceto its length-for instance, at a point, b, Fig. 2-it will be necessaryto mend the same. This may be done by placing the two sections of thefilament in adepositionyet, 0, the parts being held near the broken endsby the clamps c c. A battery or other source of electricity has itsrespective poles connected with the arms 0 c, and this completesitscircuit with the broken ends of the filament, which are held togetherin the deposition-vat containing a carbon or hydrocarbon in solution,and a deposit is made, the two ends uniting them firmly together.

I claim as my invention The hereinbefore-described method of treat ingcarbons, which consists in raising them to a high temperature byelectric currents, and purposely causing them to break by reason of suchtemperature, thereby giving them a permanent set.

1n testimony whereof I have hereunto sub scribed my name this 17th dayof August, A. I). 1886.

EDWARD I. THOMPSON.

Witnesses:

DANL. W. EDGEGOMB, CHARLES A. TERRY.

